/* ========================================
   THEME SYSTEM: LIGHT & DARK
   ======================================== */
:root {
  --font-display: 'IBM Plex Sans', 'Helvetica Neue', Arial, sans-serif;
  --font-body: 'IBM Plex Sans', 'Helvetica Neue', Arial, sans-serif;
  --font-accent: 'IBM Plex Serif', 'Georgia', serif;
  --font-mono: 'IBM Plex Mono', 'SF Mono', 'Fira Code', monospace;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --focus-ring: 0 0 0 3px rgba(195, 147, 68, 0.5);
  --transition: 0.25s ease;
}

:root,
[data-theme='light'] {
  --bg: #faf7f2;
  --bg-surface: #ffffff;
  --text-primary: #2c2825;
  --text-body: #4a4540;
  --text-muted: #7a756e;
  --accent: #c39344;
  --accent-soft: rgba(195, 147, 68, 0.08);
  --accent-medium: rgba(195, 147, 68, 0.25);
  --border: #e5e0d8;
  --hover-surface: rgba(195, 147, 68, 0.04);
  --callout-bg: #f5f1eb;
  --disclaimer-bg: rgba(195, 147, 68, 0.06);
  --tldr-bg: linear-gradient(135deg, #f5f1eb 0%, #ede7db 100%);
  --tldr-bg-flat: #f0ece4;
  --img-shadow: 0 4px 24px rgba(0, 0, 0, 0.1);
  --toggle-bg: #e5e0d8;
  --toggle-fg: #2c2825;
  --cta-bg: linear-gradient(135deg, #2c2825 0%, #1a1715 100%);
  --cta-heading: #d4a854;
  --cta-text: rgba(250, 247, 242, 0.75);
  --cta-btn-bg: #c39344;
  --cta-btn-text: #fff;
  --cta-btn-hover-shadow: 0 6px 20px rgba(195, 147, 68, 0.35);
}

[data-theme='dark'] {
  --bg: #1a1816;
  --bg-surface: #242120;
  --text-primary: #f0ece4;
  --text-body: #c8c2b8;
  --text-muted: #8a847c;
  --accent: #d4a854;
  --accent-soft: rgba(212, 168, 84, 0.1);
  --accent-medium: rgba(212, 168, 84, 0.25);
  --border: #3a3530;
  --hover-surface: rgba(212, 168, 84, 0.06);
  --callout-bg: #2a2725;
  --disclaimer-bg: rgba(212, 168, 84, 0.08);
  --tldr-bg: linear-gradient(135deg, #2a2622 0%, #322e28 100%);
  --tldr-bg-flat: #2a2622;
  --img-shadow: 0 4px 24px rgba(0, 0, 0, 0.4);
  --toggle-bg: #3a3530;
  --toggle-fg: #f0ece4;
  --cta-bg: linear-gradient(135deg, #322e28 0%, #252220 100%);
  --cta-heading: #d4a854;
  --cta-text: #a09888;
  --cta-btn-bg: #d4a854;
  --cta-btn-text: #1a1816;
  --cta-btn-hover-shadow: 0 6px 20px rgba(212, 168, 84, 0.3);
}

/* ========================================
   ACCESSIBILITY: READING CONTROLS
   ======================================== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  font-size: var(--reading-size, 1.05rem);
  line-height: var(--reading-line-height, 1.8);
  letter-spacing: var(--reading-letter-spacing, 0.01em);
  word-spacing: var(--reading-word-spacing, 0.02em);
  color: var(--text-body);
  background: var(--bg);
  transition:
    background var(--transition),
    color var(--transition);
  -webkit-font-smoothing: antialiased;
}

/* Per-page body font-face override from the toolbar */
body[data-font-face='serif'] {
  font-family: var(--font-accent);
}
body[data-font-face='sans'] {
  font-family: var(--font-body);
}
body[data-font-face='dyslexia'] {
  font-family: 'Atkinson Hyperlegible', 'Comic Sans MS', sans-serif;
}

/* Skip-to-content link for screen readers */
.skip-link {
  position: absolute;
  top: -100%;
  left: 1rem;
  background: var(--accent);
  color: #fff;
  padding: 0.75rem 1.5rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  z-index: 1000;
  text-decoration: none;
}
.skip-link:focus {
  top: 1rem;
  outline: none;
  box-shadow: var(--focus-ring);
}

/* Focus styles for keyboard navigation */
:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}

/* ========================================
   READING TOOLBAR + ACCESSIBILITY CONTROLS
   ======================================== */
.reading-toolbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: color-mix(in srgb, var(--bg) 92%, transparent);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--border);
  padding: 0.6rem 1rem;
  margin: 0 0 1.5rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem 1.1rem;
  font-family: var(--font-body);
}

.reading-toolbar .rt-group {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0 0.25rem;
  border-right: 1px solid var(--border);
}
.reading-toolbar .rt-group:last-child {
  border-right: 0;
}

.reading-toolbar .rt-label {
  font-size: 0.78rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--text-muted);
  margin-right: 0.2rem;
}

.reading-toolbar .rt-btn {
  background: transparent;
  color: var(--text-body);
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  padding: 0.32rem 0.7rem;
  font: 600 0.82rem/1 var(--font-body);
  cursor: pointer;
  transition: all var(--transition);
  min-height: 36px;
  min-width: 36px;
}
.reading-toolbar .rt-btn:hover {
  background: var(--accent-soft);
  border-color: var(--accent-medium);
}
.reading-toolbar .rt-btn:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
}
.reading-toolbar .rt-btn.is-active,
.reading-toolbar .rt-btn[aria-pressed='true'] {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

.reading-toolbar .rt-rate {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.78rem;
  color: var(--text-muted);
}
.reading-toolbar .rt-rate select {
  background: var(--bg-surface);
  color: var(--text-body);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.25rem 0.5rem;
  font: 600 0.82rem var(--font-body);
  min-height: 32px;
}

.reading-toolbar [data-audio-status] {
  font-size: 0.78rem;
  color: var(--text-muted);
  font-style: italic;
}

.reading-toolbar .rt-group.is-unavailable {
  opacity: 0.4;
  pointer-events: none;
}

.reading-toolbar .back-link {
  color: var(--text-body);
  text-decoration: none;
  font-size: 0.85rem;
  font-weight: 600;
  margin: 0;
}
.reading-toolbar .back-link:hover {
  color: var(--accent);
}
.reading-toolbar .back-link::before {
  content: '';
  margin: 0;
}

/* Screen-reader-only utility */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Toast — transient confirmation (e.g. share actions) */
.a11y-toast {
  position: fixed;
  left: 50%;
  bottom: 1.5rem;
  transform: translateX(-50%) translateY(1rem);
  background: var(--text-primary);
  color: var(--bg);
  font: 600 0.9rem/1.45 var(--font-body);
  padding: 0.8rem 1.25rem;
  border-radius: var(--radius-sm);
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.32);
  max-width: min(90vw, 440px);
  text-align: center;
  z-index: 9500;
  opacity: 0;
  pointer-events: none;
  transition:
    opacity 0.25s ease,
    transform 0.25s ease;
}
.a11y-toast.is-visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* Point-to-zoom magnifier */
.magnifier-lens {
  position: fixed;
  width: 480px;
  height: 480px;
  border-radius: 12px;
  border: 3px solid var(--accent);
  box-shadow:
    0 14px 36px rgba(0, 0, 0, 0.32),
    0 0 0 6px rgba(0, 0, 0, 0.08);
  background: var(--bg);
  overflow: hidden;
  pointer-events: none;
  z-index: 9000;
}

.magnifier-inner {
  position: absolute;
  top: 0;
  left: 0;
  width: 780px;
  transform-origin: 0 0;
  will-change: transform;
  pointer-events: none;
}

.magnifier-inner > .article-layout,
.magnifier-inner > main {
  margin: 0;
  padding: 2rem 1.5rem 4rem;
  background: transparent;
}

body[data-magnifier='on'] {
  cursor: crosshair;
}
body[data-magnifier='on'] .reading-toolbar {
  cursor: auto;
}

/* Currently-reading paragraph highlight during TTS playback */
.is-reading {
  background: var(--accent-soft);
  outline: 2px solid var(--accent-medium);
  outline-offset: 4px;
  border-radius: var(--radius-sm);
}

@media (max-width: 600px) {
  .reading-toolbar {
    padding: 0.5rem 0.6rem;
    gap: 0.35rem 0.6rem;
  }
  .reading-toolbar .rt-group {
    border-right: 0;
    padding: 0 0.15rem;
  }
  .reading-toolbar .rt-label {
    display: none;
  }
}

/* ========================================
   ARTICLE LAYOUT
   ======================================== */
.article-layout {
  max-width: 780px;
  margin: 0 auto;
  padding: 2rem 1.5rem 4rem;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-weight: 600;
  color: var(--accent);
  margin-bottom: 2rem;
  text-decoration: none;
  transition: color var(--transition);
}
.back-link:hover {
  color: var(--text-primary);
}
.back-link::before {
  content: '←';
}

.article-meta {
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
  margin-bottom: 1.5rem;
}

.tag {
  background: var(--accent-soft);
  border: 1px solid var(--accent-medium);
  color: var(--accent);
  padding: 0.25rem 0.65rem;
  border-radius: 20px;
  font-size: 0.78rem;
  font-weight: 600;
  letter-spacing: 0.03em;
}

h1 {
  font-family: var(--font-display);
  font-size: clamp(1.8rem, 3vw + 1rem, 2.8rem);
  line-height: 1.2;
  color: var(--text-primary);
  margin: 0 0 1rem;
  transition: color var(--transition);
}

h2 {
  font-family: var(--font-display);
  font-size: 1.5rem;
  color: var(--text-primary);
  margin: 2.5rem 0 1rem;
  transition: color var(--transition);
}

h3 {
  font-family: var(--font-display);
  font-size: 1.2rem;
  color: var(--text-primary);
  margin: 2rem 0 0.75rem;
  transition: color var(--transition);
}

p {
  margin-bottom: 1.25rem;
}

.lead {
  font-size: calc(var(--reading-size, 1.05rem) + 0.07rem);
  color: var(--text-muted);
  margin-bottom: 2rem;
  border-left: 3px solid var(--accent);
  padding-left: 1.25rem;
}

ul,
ol {
  padding-left: 1.3rem;
  margin-bottom: 1.25rem;
}
li {
  margin-bottom: 0.5rem;
}
li::marker {
  color: var(--accent);
}
strong {
  color: var(--text-primary);
}

blockquote {
  border-left: 3px solid var(--accent);
  padding: 1rem 1.5rem;
  margin: 1.5rem 0;
  background: var(--accent-soft);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}
blockquote p {
  margin: 0;
  font-weight: 500;
}

code {
  font-family: var(--font-mono);
  background: var(--accent-soft);
  padding: 0.15rem 0.4rem;
  border-radius: 4px;
  font-size: 0.9em;
}

/* ========================================
   TL;DR BOX
   ======================================== */
.tldr {
  background: var(--tldr-bg);
  border: 1px solid var(--accent-medium);
  border-radius: var(--radius-md);
  padding: 1.75rem 2rem;
  margin-bottom: 2.5rem;
  position: relative;
  overflow: hidden;
  transition: border var(--transition);
}
.tldr::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 4px;
  height: 100%;
  background: linear-gradient(180deg, var(--accent) 0%, rgba(195, 147, 68, 0.3) 100%);
  border-radius: 4px 0 0 4px;
}
.tldr__title {
  font-family: var(--font-display);
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--accent);
  margin-bottom: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  letter-spacing: 0.02em;
}
.tldr ul {
  margin-bottom: 0;
}
.tldr li {
  font-size: 0.95rem;
  margin-bottom: 0.6rem;
}
.tldr li:last-child {
  margin-bottom: 0;
}

/* ========================================
   DISCLAIMER
   ======================================== */
.disclaimer {
  background: var(--disclaimer-bg);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.5rem;
  margin-bottom: 2rem;
  font-size: 0.9rem;
  color: var(--text-muted);
  border: 1px solid var(--accent-medium);
  transition: all var(--transition);
}
.disclaimer strong {
  color: var(--text-primary);
}

/* ========================================
   CALLOUTS
   ======================================== */
.callout {
  background: var(--callout-bg);
  border: 1px solid var(--accent-medium);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  margin: 1.5rem 0;
  transition: all var(--transition);
}
.callout h4 {
  font-family: var(--font-display);
  color: var(--accent);
  margin: 0 0 0.5rem;
}

/* ========================================
   FIGURES / DIAGRAMS
   ======================================== */
.article-figure {
  margin: 2rem 0;
  text-align: center;
}
.article-figure img {
  max-width: 100%;
  height: auto;
  border-radius: var(--radius-md);
  box-shadow: var(--img-shadow);
  transition: box-shadow var(--transition);
}
.article-figure figcaption {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 0.75rem;
  font-style: italic;
}

/* High contrast mode for images in dark theme */
[data-theme='dark'] .article-figure img {
  filter: brightness(0.92) contrast(1.05);
}

/* ========================================
   CTA BOX
   ======================================== */
.article-cta {
  background: var(--cta-bg);
  border: 1px solid var(--accent-medium);
  border-radius: var(--radius-lg);
  padding: 2.75rem 2.5rem;
  margin-top: 3rem;
  text-align: center;
  position: relative;
  overflow: hidden;
}
.article-cta::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, transparent, var(--accent), transparent);
}
.article-cta h3 {
  color: var(--cta-heading);
  margin-top: 0;
  margin-bottom: 0.75rem;
  font-family: var(--font-display);
  font-size: 1.4rem;
}
.article-cta p {
  color: var(--cta-text);
  margin-bottom: 1.25rem;
  font-size: 1rem;
}
.article-cta .btn {
  display: inline-block;
  background: var(--cta-btn-bg);
  color: var(--cta-btn-text);
  padding: 0.8rem 2.25rem;
  border-radius: var(--radius-sm);
  text-decoration: none;
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: 0.02em;
  transition:
    transform 0.2s,
    box-shadow 0.2s;
}
.article-cta .btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--cta-btn-hover-shadow);
}
.article-cta .btn:focus-visible {
  box-shadow: var(--focus-ring);
}

/* ========================================
   RESPONSIVE
   ======================================== */
@media (max-width: 640px) {
  .toolbar {
    padding: 0.5rem 1rem;
  }
  .toolbar__label {
    display: none;
  }
  .article-layout {
    padding: 1.5rem 1rem 3rem;
  }
}

/* ========================================
   REDUCED MOTION
   ======================================== */
@media (prefers-reduced-motion: reduce) {
  * {
    transition-duration: 0.01ms !important;
  }
}

/* ========================================
   HIGH CONTRAST MODE (prefers-contrast)
   ======================================== */
@media (prefers-contrast: more) {
  :root {
    --text-body: #1a1816;
    --border: #888;
  }
  [data-theme='dark'] {
    --text-body: #f5f3f0;
    --border: #666;
  }
}